In a laser welding method in which workpieces are lap-welded by irradiation of a laser beam, in order to increase a gap tolerance between the workpieces, a laser welding method in which a wide range of workpieces is irradiated with a laser beam to enlarge a molten pool and to fill a gap between the workpieces has been widely used. However, when the wide range of workpieces is irradiated with the laser beam, bubbles are generated inside the molten pool, and strength of a welded portion significantly lowers. Accordingly, a plurality of methods for removing bubbles generated inside a molten pool has been proposed.
PTL 1 discloses a method in which a molten pool is irradiated with a laser beam to stir a molten pool and to remove bubbles. Furthermore, PTL 2 discloses a method in which pores within a solidified molten metal are eliminated by remelting. Furthermore, PTL 3 discloses a method in which, of a laser irradiation step, bubbles generated in an initial stage where an output of a laser beam is low and in a middle stage where the output of the laser beam is high are discharged in a later stage where the output of the laser beam is low.